Small Base Die Explanation

If you have the Lee Pacesetter die set with a full length-sizing die, you shouldn’t need a small base die. Other manufacturers make small base dies on the premise that semi-autos require cases sized to the minimum allowable case dimension for reliable feeding, but in reality most semi-autos have chambers cut on the large side for that same purpose. The result is overworked brass and shortened case life. If you have any chambering problems with ammunition that has been sized with a Lee full length sizing die, return the die and a couple fired cases to the factory for free adjustment.

Lee’s address is;

Lee Precision Inc,
4275 Hwy. U,
Hartford, WI 53027.